Method for producing β-fluoroalcohol
A production method of a β-fluoroalcohol includes performing a reaction of an α-fluoroester with hydrogen gas (H 2 ) in the presence of a specific ruthenium complex (i.e. a ruthenium complex of the general formula [2], preferably a ruthenium complex of the general formula [4]). This production method can employ a suitable hydrogen pressure of 1 MPa or less by the use of such a specific ruthenium complex and does not require a high-pressure gas production facility when put in industrial practice. In addition, this production method can remarkably reduce the amount of catalyst used therein (to e.g. a substrate/catalyst ratio of 20,000) in comparison to the substrate/catalyst ratio conventional reduction of α-fluoroalcohol. It is possible by these reduction in hydrogen pressure and catalyst amount to largely reduce the production cost of the β-fluoroalcohol.
1. A method for producing a β-fluoroalcohol of the general formula [3], comprising: performing a reaction of an α-fluoroester of the general formula [1] with hydrogen gas (H 2 ) in the presence of a ruthenium complex of the general formula [2]
where R 1 and R 2 each independently represent a hydrogen atom, a halogen atom, an alkyl group, a substituted alkyl group, an aromatic ring group, a substituted aromatic ring group, an alkoxycarbonyl group or a substituted alkoxycarbonyl group; and R 3 represents an alkyl group or a substituted alkyl group
where R each independently represent a hydrogen atom, an alkyl group, a substituted alkyl group, an aromatic ring group or a substituted aromatic ring group; Ar each independently represent an aromatic ring group or a substituted aromatic ring group; X each independently represent a ligand having a formal charge of −1 or 0 (wherein a sum of formal charges of three X is −2); and n each independently represent an integer of 1 or 2
2. The method according to claim 1 , wherein the reaction is performed in the presence of a base.
3. The method according to claim 2 , wherein the ruthenium complex of the general formula [2] is a ruthenium complex of the general formula [4]
where Ph represent a phenyl group.
4. The method according to claim 1 , wherein the α-fluoroester of the general formula [1] is an α-fluoroester of the general formula [5]; and wherein the β-fluoroalcohol of the general formula [3] is a β-fluoroalcohol of the general formula [6]
where R 4 represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aromatic ring group or a substituted aromatic ring group; and R 5 represents an alkyl group
5. The method according to claim 1 , wherein the α-fluoroester of the general formula [1] is an α-fluoroester of the general formula [7]; and wherein the β-fluoroalcohol of the general formula [3] is a β-fluoroalcohol of the general formula [8]
where Me represents a methyl group
6. The method according to claim 1 , wherein the reaction is performed at a hydrogen pressure of 3 MPa or lower.
7. The method according to claim 6 , wherein the reaction is performed at a hydrogen pressure of 2 MPa or lower.
8. The method according to claim 7 , wherein the reaction is performed at a hydrogen pressure of 1 MPa or lower.